This research seeks to determine antibody-mediated immunity (AMI) and cell-mediated immunity (CMI) in infants and children with acute otitis media. Attempts will be made to determine specific reactivity of both local and systemic limbs of the immune system. Evidence suggests that the middle ear has an immune capacity which operates on occasion independent of the systemic immune system. The capability exists to sensitize the middle ear by oral as well as parenteral immunization. In addition there appears to exist an IgA memory system. Other data suggests that a type I hypersensitivity reaction may be the cause of acute pneumococcal otitis media in infants. This is based on elevated levels of IgE in middle fluid when compared to simultaneously drawn serum, the ability to adsorb out approximately one-half of the IgE with ultrasonicates of S. pneumoniae, and the ability to specifically induce a wheal and flare reaction in human skin sensitized with middle ear fluid and challenged with the ultrasonicates of S. pneumoniae. Studies are underway to determine the number and etiology of subsequent episodes of otitis media in patients receiving various types of chemotherapy and in patients who have been immunized with an octavalent preparation of pneumococcal capsular polysaccharides. BIBLIOGRAPHIC REFERENCES: Sloyer, J.L. Jr., Ploussard, J.H., Howie, V.M. Immunology and Microbiology in Acute Otitis Media. Ann. Otol. Rhinol. Laryngol. 85(S25): 254-258, 1976. Howie, V.M., Ploussard, J.H. , Sloyer, J.L. Jr. Immunization against Recurrent Otitis Media Ann. Otol. Rhinol. Laryngol. 85(S25): 254-258, 1976.